For days, Sen. Marco Rubio's presidential campaign has been touting an end-of-the-year, multi-day bus tour across Iowa, the first state in the nation to vote. But one key element will largely be missing from the first day of the campaign swing: a bus.

When the Republican candidate travels today between three cities across Iowa, hundreds of miles apart, he’ll traverse the distances on a private plane, according to his campaign. Rubio’s bus was expected to make its first appearance on Wednesday at three stops, but it showed up at Rubio’s first event today. It stayed behind, though, as the senator flew to his next stops.

"There will be some chartering on the campaign’s plane on some of the stops to maximize the reach and some of it will be driving," Rubio’s director of communications, Alex Conant, told ABC News.

But last week, when details of the trip were released, the campaign said Rubio would "be spending three days, December 28 - 30, traveling around Iowa on his campaign bus” — with seven events along the way. The Florida senator was forced to cancel Day One of the tour on Monday due to a powerful winter storm.

In Iowa, a Dec. 14 Quinnipiac University Poll of likely Republican caucus-goers, shows Rubio with 14 percent support -- well-behind Donald Trump and fellow GOP senator Ted Cruz, who both lead him by nearly double. Next week, Cruz will embark on a 36-county campaign swing through the Hawkeye State after a nearly month-long absence.

"While other candidates have been largely absent from Iowa in December, Marco is spending time meeting voters and doing what we need to do to succeed in February,” Conant said.

Rubio has ramped up his visits here over the last couple months — holding around two dozen events — and his campaign says he’ll spend a lot of time in the state in January.

This week, Rubio will be joined by Rep. Trey Gowdy, R-South Carolina, on all of his stops, according to his campaign. Gowdy heads the GOP-led investigation into the 2012 Benghazi attacks, and Trump went after him on Sunday for backing Rubio.